AGN Don't Produce the IceCube Neutrino Flux

Recent IceCube observations of the flaring blazar TXS 0506+056 have excited the community, potentially providing the first detection of a neutrino source. Additionally, the detection of neutrino emission from a blazar might indicate that blazars dominate the neutrino background. Here, however, we utilize detailed catalogs of optically and gamma-ray bright blazars, including a huge population of source that could potentially produce the diffuse IceCube neutrino emission. We find no evidence of neutrino hotspots associated with the known positions of blazars, and use this lack of correlation to rule out models where more than approximately 20% of the diffuse IceCube neutrino background is produced by blazar activity.

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No Evidence of Neutrinos from the Fermi Bubbles

A recent analysis argued that the Fermi bubbles morphologically matches an excess in the morphology of IceCube neutrino events. We re-investigate this scenario, finding no evidence for such a scenario after the IceCube effective exposure is carefully considered. We note more generally that a combination of the IceCube neutrino flux and HAWC observations of TeV gamma-rays can constrain the leptonic or hardonic morphology of the bubbles, and show that there is presently no strong evidence for any IceCube neutrino flux from the Fermi bubbles region.

Full Publication List:

3. Active Galactic Nuclei and the Origin of IceCube’s Diffuse Neutrino Flux
Dan Hooper, Tim Linden, Abby Vieregg
Journal of Cosmology and Astroparticle Physics 02 012

2. IceCube and HAWC Constraints on Very-High-Energy Emission from the Fermi Bubbles
Ke Fang, Meng Su, Tim Linden, Kohta Murase
Physical Review D 96 123007

1. Is the Ultra-High Energy Cosmic-Ray Excess Correlated with IceCube Neutrinos?
Ke Fang, Toshihiro Fujii, Tim Linden, Angela Olinto
The Astrophysical Journal, 794 126

Tim Linden

Assistant Professor, Stockholm University